This invention relates to an apparatus and method for remediation of soils and other materials contaminated with organic and other compounds. The invention is of the type that employs dual volatilizing zones and radiant heat.
Such structures, according to this invention, generally will substantially volatilize organic and other compounds contained within the material, and substantially eliminate harmful pollutants from the exhaust fumes. In preferred embodiments, a volatilizer is comprised of three concentric, rotating cylinders, such that the material traverses several distinct drying zones and undesirable organic compounds are volatilized as the cylinders rotate.
It is known, in material heating/drying systems, to make use of a system including a rotating drum and an open flame heater, such that as the material traverses the length of the system, the material is heated/dried. In each of these cases a great expenditure of energy is required to reach the desired temperature, in order to adequately treat the material, and the fumes that are exhausted from the heating and/or drying process must be filtered to remove harmful pollutants.
Exemplary of such prior art heating/drying systems are devices as disclosed in U.S. Pat. Nos. Re. 30,685 to Mendenhall and 1,041,226 to Ames, as well as well-known devices of the single-zone radiant heat/drier type. The Mendenhall patent discloses a process for recycling asphalt aggregate compositions which is comprised of a rotatable drum, a firing chamber, heating tubes and means to transport volatile gases from the mixing chamber to the firing chamber. The Ames patent, as another alternative, discloses a machine for treating bituminous or asphaltic compounds which is comprised of an open-flame heater, a material lifting means and a rotating cylindrical drum having a series of cylinders surrounding a central cone, such that the material is fed into the cylinders at one end of the machine and is discharged from the cone at that same end of the machine.
While these two systems are capable of heating/drying the material, they are made up, of necessity, of numerous parts. Due to the sheer number of these parts and their complex arrangements, all necessary to properly heat the material, the material is not efficiently heated. For this reason, a large amount of energy is needed to initially heat and then to maintain the correct temperature in the cylindrical drum, due in part to the large surface area of the heating tubes and cylinders contained within the respective drums. A system which did not require the expenditure of these amounts of energy would be highly desirable.
Single-zone radiant heater/driers are well-known. Generally speaking, such devices are usually comprised of a cylindrical drum, a radiant heater, and means to traverse the length of the drum in a single pass while the material is being heated/dried. While such systems are currently in use, they suffer from the problem that not all the undesirable volatile organic compounds are volatilized from the material, because the required temperature is often not reached. Conversely, in order to achieve the desired temperature, a large amount of fuel must be expended. Consequently, either the material must be treated again, or extra fuel must be used. Either way, the process becomes expensive. A system which neared the relative simplicity of this system, but overcomes its above-described problems, would be most desirable.
It is apparent from the above that there exists a need in the art for a material volatilizer which is fuel-efficient, through simplicity of parts and uniqueness of structure, and which at least equals the safety characteristics of known heater/driers, but which at the same time adequately treats the material so as to substantially volatilize the organic compounds contained in the material. It is a purpose of this invention to fulfill this and other needs in the art in a manner more apparent to the skilled artisan, once given the following disclosure.